The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
Sealing arrangements are generally utilized around a perimeter of a movable object especially in applications requiring sealing against environmental factors such as moisture, wind, and dust. They consist of materials such as rubber or brush, which are suitable to close required gaps between the movable object and a surrounding structure, yet enable low frictional forces during movement.
Most typical applications using such sealing arrangements include exterior doors of a swing or pivot type used in buildings and transit vehicles.
The use of such sealing arrangement in conjunction with the present invention will be explained as used in a particular application within a transit vehicle.
Door systems of a slide-glide arrangement are well known in the art of transit vehicles in general and buses in particular. Such door systems include at least one door disposed within a portal aperture for at least partially covering and uncovering such portal aperture for passenger ingress and egress. The at least one door has top and bottom pivotal attachments to a door post which is vertically disposed at the edge of such portal aperture. The door post is connected to a door operator and is adapted for a 180 degree rotation.
The at least one door is constrained for linear movement of a leading edge by the top bracket and typically contains a sealing means, such as a brush, at the bottom thereof for sealing against environmental factors. The portal aperture is disposed adjacent an interior floor portion and typically incorporates an outer edge of the floor portion as a bottom edge thereof.
For uncovering the portal aperture, such at least one door is rotatable by the combination of the door operator and the door post from a first position being disposed substantially planar within such portal aperture to a second position being disposed perpendicular to the portal aperture and further being disposed within the interior portion of such transit vehicle. In such second position such at least one door is disposed above the floor portion of such transit vehicle and its leading edge is facing outwardly toward the exterior of the transit vehicle.
In a traditional design of the transit vehicle the floor portion adjacent such portal aperture is disposed substantially leveled with the ground enabling constant interface with the bottom edge of the at least one door during rotational movement.
Lately, new types of transit vehicles employ sloped floor portions for an improved transition between the ground level and the main floor portion. The slope begins at such portal aperture and elevates toward a main floor portion. It is well known in such transit vehicles, that a sealing arrangement at the bottom edge of such at least one door must accommodate the sloped floor portion being disposed in a second position and accommodate a level edge of such floor portion being in the first position.
Traditional means of accomodating a sloped floor employ an increased gap between the bottom edge of such at least one door with increased height of the sealing arrangement to enable the bottom edge of the at least one door to clear the sloped floor portion. However, such arrangement causes bending of the sealing arrangement and further causes premature wear and deterioration thereof.